Latest news with #gammaRayBurst
Yahoo
13-07-2025
- Science
- Yahoo
Mysterious Signals From Deep Space Hint at Something Brutal, Scientists Say
Astronomers believe they've uncovered the source behind mysterious cosmic signals known as fast X-ray transients (FXTs) — and it adds a grim twist to our understanding of the death of stars. Right as a massive star explodes in a supernova, it unleashes a tremendously energetic stream of particles called a jet, producing a gamma ray burst — one of the most powerful explosions in the universe. The rest of the star, typically, collapses into a black hole. But a pair of new studies suggests that this last gasp by a star before winking out of existence can get "trapped" by some of the star's own remains, slamming the door shut on the jet so it can't fully shine. "As the jet is being launched, that extra material from the star that didn't collapse into the black hole [interacts] with the jet in such a way that sort of suppresses the jet from actually breaking out of the outer layers," Jillian Rastinejad, an astronomer at Northwestern University and lead author of one the two studies set to published in the The Astrophysical Journal Letters, told Gizmodo. That produces the weaker X-ray emissions, in the form of an FXT, which can last from seconds to hours. The nickname astronomers have for these weakened blasts is nearly as brutal as the catastrophic event itself: a "failed" jet. According to the findings, FXTs arise from a type of stellar explosion called a Type Ic supernova, which occurs in stars that have long shed their outermost layers of hydrogen and helium. Because of their ephemeral nature and the extreme distance of most detected FXTs to date, pinpointing their origins has been a challenge for astronomers. Rastinejad and her team's breakthrough came when data collected in the Einstein Probe, an X-ray telescope program run by the Chinese Academy of Sciences in collaboration with the European Space Agency, revealed an FXT that was unusually close to Earth — a mere 2.8 billion light years away. Dubbed EP 250108a, telescopes including the Keck Observatory in Hawai'i and the James Webb Space Telescope rushed to extensively image the X-ray burst in multiple wavelengths, collecting infrared and optical data. "It's important to note that X-ray data alone cannot tell us what phenomena created an FXT," Rastinejad said in a statement about the work. "Rapid observations of the location of the FXT at optical and infrared wavelengths are key to identifying the aftermath of an FXT and assembling clues to its origin." With that wealth of data, the astronomers were able to observe how the signal evolved over time. Over the course of several weeks, the stunted supernova increased in brightness before eventually fading. The brief peak in brightness allowed the astronomers to determine that the blast was a Type Ic supernova — and one that was clearly lacking a gamma ray burst. This has profound implications for our understanding of a star's demise, because according to the work, with sufficiently large stars — the one that produced EP 250108a is estimated to be between 15 to 30 times heavier than the Sun — the full-blown gamma ray bursts we've come to equate with supernovas may not actually be the norm. Instead, Rastinejad said, "this 'trapped' jet outcome is more common in massive star explosions than jets that successfully emerge from the star." More on space: Astronomers Capture First-Ever Image of Star That Exploded Twice
Gizmodo
09-07-2025
- Science
- Gizmodo
Mysterious Signals From Deep Space Expose Aftermath of Failed Cosmic Eruptions
Whenever we study space, we're usually talking about long-lasting objects, like our own solar system or faraway galaxies that occasionally catch our attention when something extraordinary happens. But sometimes, the universe sends us quick, random bursts of energy that are usually too far away and too ephemeral for scientists to make any sense of—like fast X-ray transients (FXTs), whose elusive origins have long evaded astronomers. Recently, however, astrophysicists had a lucky strike: spotting an FXT flashing unprecedentedly close to Earth and for a marginally longer time than usual. Not only that, but the X-ray burst, later named EP 250108a, seemed to be a faint spillover signal—likely the result of a cosmic jet—that barely escaped the powerful gravitational binds of a supernova. Using multiple space telescopes around the world, an international team of astrophysicists from Northwestern University and the University of Leicester in England found compelling evidence that EP 250108a may have originated from the 'failed' jets of a gamma-ray burst, likely triggered by the explosive death of a star around 2.8 billion light-years from Earth. Their results—presented in two papers set for publication in The Astrophysical Journal Letters—offer some of the best evidence yet for at least one potential origin for fast X-ray transients (FXTs are distinct from fast radio bursts (FRBs), brief, extremely energetic bursts of radio waves with wavelengths much longer than those of X-rays). When a star explodes in a fiery supernova, it swallows almost everything in its vicinity, eventually collapsing into a black hole. In this process of accretion, the star takes on an onion-like form, with different layers of gas, dust, and other cosmic material jostled around by gravitational forces. Some of this material escapes, usually in the form of jets that generate gamma-ray bursts, a class of the most powerful and luminous explosions in the universe. But sometimes, the outer layers of an 'onion-shaped' supernova exert a strong gravitational barrier on the gamma-ray bursts. In the case of this FXT, the tiny bits of energy that managed to leak through probably created EP 250108a, explained Jillian Rastinejad, a PhD student at Northwestern University and lead author of the new paper, in a video call with Gizmodo. 'As the jet is being launched, that extra material from the star that didn't collapse into the black hole [interacts] with the jet in such a way that sort of suppresses the jet from actually breaking out of the outer layers,' she said. Rastinejad and colleagues first spotted EP 250108a in January using data from the Einstein Probe, a collaborative project between China and Europe tasked specifically with the observation of FXTs and other 'fleeting' cosmic phenomena. Einstein Probe detects on average 'maybe one [FXT] every three days or so,' Rastinejad recounted, but some of her collaborators followed it up with optical telescopes and found that this particular transient was unusually close to Earth. 'When something's really nearby, it means that it's going to be a lot brighter,' she explained. 'So we can do a really detailed, beautiful, comprehensive, super exciting study of what else is going on at the location of the fast X-ray transient.' 'It's always very exciting when there's a transient object, just because it's like there's this sound of the record stopping, and you've got to stop what you're doing and move over there,' said John O'Meara, deputy director and chief scientist at the W.M. Keck Observatory in Hawaii, during a video call with Gizmodo. Keck Observatory was one of several huge space telescopes Rastinejad and colleagues pointed toward EP 250108a, allowing the team to capture a high-resolution view of the ephemeral object before it fades to oblivion. Unlike most astronomical phenomena of interest to scientists—which lie on timescales that far exceed human lifespans—fast X-ray transients are part of the rare family of cosmic phenomena that evolve on a 'human timescale,' Rastinejad said. 'If you took a picture of our Milky Way today, and you took a picture of it maybe a thousand years ago, it would look the same,' she explained. 'But if you studied one type of massive star like we studied here, it changes a lot in what it looks like across the wavelengths on very human timescales.' 'The universe keeps trying to tell us very interesting things,' added O'Meara. But the universe 'doesn't care what telescope you build, but [EP 250108a] is a good example of proving that we're ready to rise to the challenge of whatever the universe wants to throw at us—and I hope we get to keep doing that into the coming decades.' In fact, Rastinejad, who just finished defending her PhD thesis, already has her eyes on another odd signal from the universe. 'Just a few days ago, [Einstein Probe] saw a fast X-ray transient that occurred in the same part of the sky at the same time as a signal from neutron star mergers,' she said excitedly. 'Astronomy is like art. It doesn't really affect our day-to-day lives. But it answers these questions that humans have always wondered about: where we come from and where we're going.'
Yahoo
09-07-2025
- Science
- Yahoo
Dying Star's Strangled Jets Solve 50-Year-Old X-Ray Mystery
Jets that failed to punch through the outer shell of a dying star are the sources of mysterious X-ray flashes that have puzzled astronomers for decades. A new study of a star undergoing the throes of a supernova death has revealed that bursts of X-radiation known as fast-X-ray transients (FXTs) are the result of a failed gamma-ray burst (GRB) – the most energetic explosions our Universe can produce. "Since the 1970s, astronomers have detected FXTs – blasts of X-rays from distant galaxies that can last from seconds to hours," says astronomer Jillian Rastinejad of Northwestern University in the US. "But their sources have remained a long-standing mystery. Our work definitively shows that FXTs can originate from the explosive death of a massive star. It also supports a causal link between GRB-supernovae and FXT-supernovae, in which GRBs are produced by successful jets, and FXTs are produced by trapped weak jets." Related: A supernova is not one single, done-and-dusted affair; the eventual implosion of the stellar core, and outward expulsion of the material around it, are presaged by a long period of instability in which the star shucks its outer layers. When the star does eventually hit that supernova point, jets blast outward from the collapsing core, punching through the outer layers and out into interstellar space. Those jets are what produce the GRBs, causing the material around the star to blaze with radiation as it is shocked by the powerful outflows. The detection of an event on 8 January 2025 was fortuitous for our understanding of the way these energetic explosions can go wrong. An X-ray telescope on the Einstein Probe caught an FXT from 2.8 billion light-years across the Universe. Scientists immediately rushed in to take advantage of the opportunity to learn more about these enigmatic flashes, using a suite of telescopes to record the event across multiple wavelengths. "It's important to note that X-ray data alone cannot tell us what phenomena created an FXT," Rastinejad explains. "Rapid observations of the location of the FXT at optical and infrared wavelengths are key to identifying the aftermath of an FXT and assembling clues to its origin." The FXT was named EP 250108a, and, as the evolving dataset revealed over the ensuing weeks, it was associated with a supernova event named SN 2025kg – affectionately nicknamed The Kangaroo. The researchers found that the supernova was a particularly rare and energetic variety known as a Type Ic-BL supernova, originating in the core collapse of a massive star between 15 and 30 times the mass of the Sun. The observations also revealed a high-speed outward explosion of ejecta, moving at almost 19,000 kilometers (11,800 miles) per second. Such supernovae are usually the origin of GRBs, and so the researchers found. "This FXT supernova is nearly a twin of past supernovae that followed GRBs," says astrophysicist Rob Eyles-Ferris of the University of Leicester in the UK. "Our observations of the early stages of EP 250108a's evolution show that the explosions of massive stars can produce both phenomena." The team's analysis showed that, rather than punching through the layers of ejected star material as seen in a GRB, the jets that erupted from the core of this particular dying star remained trapped inside the shell of ejecta. This trapped jet still shocks and heats the cocoon around it, just not to GRB levels. Although GRBs have been seen and studied in pretty intricate detail, we don't know much about how they can fail. The discovery of EP 250108a and SN 2025kg gave astronomers the evidence they needed to estimate that, actually, the GRB failure rate is higher than success. "Through decades of scientific study, we know that jets can successfully plow through a dying star's outer layers, and we view them as GRBs," Rastinejad says. "In our study, we found this 'trapped' jet outcome is more common in massive star explosions than jets that successfully emerge from the star." This is really exciting because it means that we have a new means of probing supernova explosions. Although we now know a little more than we did about FXTs, the minutiae about how they form, and what makes a star sputter out an FXT rather than a GRB still need to be figured out. "This discovery heralds a broader understanding of the diversity in massive stars' deaths and a need for deeper investigations into the whole landscape of stellar evolution," Eyles-Ferris says. The analyses have been detailed in two papers accepted into The Astrophysical Journal Letters and available on arXiv. They can be found here and here. Alien World Discovered Provoking Its Own Hellish Apocalypse Impact That Gave Us a Moon Could Explain Why Earth Now Has Life Ice in Space Could Do Something We Thought Was Impossible
